Heat-sensitive copying systems

ABSTRACT

HEAT SENSITIVE COMPOUNDS CONTAINING HETEROCYCLIC NITROGEN ATOMS SUBSTITUTED WITH AN -OR GROUP FRAGMENT UNDER THE INFLUENCE OF VARIOUS FORMS OF ENERGY TO FORM A DYE BASE, A PROTON AND AN ALDEHYDE, THESE MATERIALS BEING USEFUL IN IMAGE REPRODUCTION.

3,832,212 Patented Aug. 27, 1974 3,832,212 HEAT-SENSITIVE COPYINGSYSTEMS Philip W. Jenkins, Donald W. Heseltine, and John D. Mee,Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. NoDrawing. Application Jan. 13, 1971, Ser. No. 106,231, now Patent No.3,770,451, which is a division of application Ser. No. 766,307, Oct. 9,1968, now Patent No. 3,615,432. Divided and this application Nov. 8,1972, Ser. No. 304,674

Int. Cl. B41m 5/00 US. Cl. 11736.7 17 Claims ABSTRACT OF THE DISCLOSUREHeat sensitive compounds containing heterocyclic nitrogen atomssubstituted with an OR group fragment under the influence of variousforms of energy to form a dye base, a proton and an aldehyde, thesematerials being useful in image reproduction.

This is a division of application Ser. No. 106,231, filed Jan. 13, 1971,now US. Pat. 3,770,451, issued Nov. 6, 1973, which in turn is a divisionof Ser. No. 766,307, filed Oct. 9, 1968, now US. Pat. 3,615,432, issuedOct. 26, 1971.

This invention relates to a novel class of organic compounds and tonovel photographic elements, compositions and processes using thesecompounds.

Various classes of dyes have known uses in different types ofphotographic systems. Perhaps one of the most common applications ofdyes is their use as spectral sensitizers in silver halide emulsions.The native sensitivity of most silver halide emulsions falls within avery limited range of the visible portion of the spectrum (generally theblue region only). However, it is known that when certain dyes are addedto silver halide emulsions, the sensitivity of the silver halideemulsion is extended to longer wavelengths. The sensitizing dyes areincorporated in the emulsion and are generally uniformly distributedthroughout the emulsion. The methods used to incorporate the dyes arewell known to those skilled in the art.

Dyes are also used to sensitize silver halide emulsions which producedirect positive images. Emulsions of this type may contain an electronacceptor and silver halide grains that have been fogged with acombination of a reducing agent and a compound of a metal more electropositive than silver. One of the advantages of such direct positiveemulsions is that the highlight areas of the images obtained with thesematerials are substantially free from fog. However, known materials ofthis type have not exhibited the high speed required for manyapplications of photography. Also, such known materials have not shownthe desired selective sensitivity, especially to radiation in the greento red region of the spectrum. Furthermore, in some instances as withknown indole cyanine dyes, the inclusion of color-forming couplers orcolored couplers in such emulsions has tended to reduce the sensitivitythereof in proportion to the length of the holding time, i.e., the timeperiod from actual making the coating and curing the emulsion. This is adecided disadvantage since such emulsions cannot be held for anysubstantial period of time but must be coated immediately as formulated.It is apparent, therefore, that there is need in the art for improveddirect positive photographic emulsions having not only good speed andselective sensitivity, but having, in addition, desirable holding orkeeping stability.

In non-silver photographic systems, bleachable dyes can be used asphotosensitive materials. Generally, these dyes are bleached inproportion to the exposure and direct positive images are attainable.Color direct positives are produced by an appropriate mixture ofphotobleachable cyan,

magenta and yellow dyes. The loss of color usually proceeds at arelative slow rate and even the use of sensitizers does not speed up theprocess enough'to'make it commercially attractive.

Dyes are also useful in thermographic systems. Recording elementsfrequently are impregnated with dyes which change color when subjectedto localized heating. The heat necessary to cause the dye to react canbe provided either by direct contact, such as hot stylus, or by exposureof a differentially radiation-absorptive graphic original to intenseradiant energy while in contact with a dye-containing heat-sensitiveelement. The heat pattern established at the irradiated original causesa corresponding visible pattern to appear in the heat-sensitive layer,without deterioration of the original. A convenient source of radiationfor thermographic reproduction is a tungsten filament lamp. Theradiation is rich in infrared as well as visible light, and the processis particularly suited to the copying of originals havinginfrared-absorptive image areas. Certain of these thermographicmaterials which have been previously described are only slightlysensitive to visible light, and, consequently, prolonged exposures arenecessary in order to produce acceptable copies. It is obvious that suchmaterials have only limited use, and, in certain instances, cannot beused at all on a commercial basis.

Still another use of dyes in sensitive photographic elements is inlayers for the reduction of halation or filtration of certainundesirable rays from the exposing radiation, either upon directexposure or for re-exposure in a photographic reversal process.Antihalation layers can be coated as backing layers on either side of atransparent support carrying the light-sensitive composition.Light-filtering layers can be coated over the light-sensitive layers orbetween such layers in multilayer elements. The dyes used for suchlayers must have the desired spectral absorption characteristics. Theyshould be easily incorporated in a water-permeable hydrophilic colloidallayer and yet firmly held in the layer so that they do not diffuse fromit either during the manufacture of the element or on storing it. It isgenerally necessary to employ light-filtering dyes which can be quicklyand readily rendered ineffective, i.e., decolorized or destroyed andremoved prior to, during, or after photographic processing. For manypurposes it is particularly convenient to employ dyes which are renderedineifective by one of the photographic baths used in processing theexposed element, such as photographic developer or fixer in the case ofsilver halide photography. Prior art dyes which have desirableabsorption characteristics have not always had good bleachingcharacteristics and reproductions made from photographic elementscontaining them have been subject to undesirable stains. Other dyes havenot had the stability in aqueous gelatin that is desired.

It is an object of this invention to provide a novel class ofenergy-sensitive compounds.

Another object of this invention is to provide novel image-formingcompositions and elements containing these compounds.

It is still another object of this invention to provide negativephotographic silver halide emulsions sensitized with these novelcompounds.

An object of this invention is also to provide heat-sensitive elementscontaining these novel compounds.

Another object is to provide novel dye-containing photobleachableelements.

Another object is to provide novel non-silver direct positive dye-bleachphotographic elements capable of producing full color photographicprints.

It is still a further object of this invention to provide photographicelements having novel bleachable filter layers.

Also, an object is to provide photographic elements having novelantihalation layers.

It is another object of this invention to provide novel processes forproducing images using novel compositions, compounds and elements.

These and other objects of the invention are accomplished with compoundshaving one of the general formulae:

wherein:

R; can be any of the following:

(a) a methine linkage terminated by a heterocyclic nucleus of the typecontained in cyanine dyes, e.g., those set forth in Mees and James, TheTheory of the Photographic Process, MacMillan, 3rd ed., pp. 198-232; themethine linkage can be substituted or unsubstituted, e.g., CI-I=, C(CH-C(C H -CH=C'H, CH=CHCH=, etc.;

(b) an alkyl radical preferably containing 1 to 8 carbon atoms includinga substituted alkyl radical;

(c) an aryl radical including a substituted aryl radical such as aphenyl radical, a naphthyl radical, a tolyl radical, etc.;

(d) a hydrogen atom;

(e) an acyl radical having the formula JFK wherein R is hydrogen or analkyl group preferably having 1 to 8 carbon atoms; (f) an anilinovinylradical such as a radical having the formula wherein R is hydrogen oralkyl; or (g) a styryl radical including substituted styryl radicals,

wherein R is hydrogen, alkyl, aryl, amino including dialkylamino such asdimethylamino;

R can be either of the following:

(a) a methine linkage terminated by a heterocyclic nucleus of the typecontained in merocyanine dyes, e.g., those set forth in Mees and James(cited above); the methine linkage can be substituted or unsubstituted;or

(b) an allylidene radical including a substituted allylidene radicalsuch as a cyanoallylidene radical, an alkylcarboxyallylidene radical oran alkylsulfonylallylidene radical;

R can be either:

(a) an alkyl radical preferably having 1 to 8 carbon atoms such asmethyl, propyl, ethyl, butyl, etc., including a substituted alkylradical such as sulfoalkyl, e.g.,

an 'aralkyl, e.g., benzyl or pyridinato-oxyalkyl salt, e.g., -(CH O--Ywherein Y is a substituted or unsubstituted pyridinium salt; (b) an acylradical, e.g.,

wherein R is an alkyl radical preferably having 1 to 8 carbon atoms oraryl radical, e.g., methyl, ethyl, propyl, butyl, phenyl, naphthyl,etc.;

(c) an aryl radical including a substituted aryl radical,

e.g., phenyl, naphthyl, tolyl, etc.;

Z represents the atoms necessary to complete a 5 to 6 memberedheterocyclic nucleus including a substituted heterocyclic nucleus whichnucleus can contain at least one additional hetero atom such as oxygen,sulfur, selenium or nitrogen, e.g., a pyridine nucleus, an indolenucleus, a quinoline nucleus, etc.; and

X represents an acid anion, e.g., chloride, bromide, iodide,perchlorate, sulfamate, thiocyanate, p-toluenesulfonate, methyl sulfate,tetrafluoroborate, etc.

These compounds are very versatile and can function in several differentmanners when used in photographic elements. They can be used assensitizers in both direct positive and negative silver halideemulsions; they are heat bleachable and thus useful in thermographicrecording elements; they are photobleachable and can be used forproducing direct positives merely by coating them on a substrate; theymake excellent antihalation layers and filter layers since they can beremoved without the use of special baths simply by subjecting them tolight for a sufficient period of time; and, when a mixture of a cyan, amagenta and a yellow dye having the above formula are coated on asupport and exposed to a colored transparency, a direct color positiveis obtained as a result of photobleaching. They are also useful inpreparing holographic elements.

The compounds of this invention are chemically altered when subjected tovarious forms of energy such as (1) electromagnetic radiation includingultraviolet, visible and infrared light, X-rays, electron beams, laserbeams, etc., (2) heat derived from various sources such as infraredradiation, (3) energy produced by mechanical means such as that producedby the local application of pressure, (4) sound waves, etc.

When the energy sensitive compounds of this invention are exposed to anyof the various forms of energy enumerated above, the pursuant alterationis generally a fragmentation of the compound molecule. It is theresultant components of the fragmentation which may be used in theformation of images. The particular route of the fragmentation reactionis somewhat dependent upon the structure of the original compound.However, based upon observations, it is believed that the route followedwhen a dye of this invention (such as the one given below) is exposed toa form of energy (such as light) is the following:

I: CHaO- 4- CHaO I" 3* crno In this case photobleaching is effected by aheterolytic cleavage of the nitrogen-oxygen (NO) bond to produce a RO+ion and a dye base which may in part fragment even farther. The dye baseis useful in image reproduction. The remaining fragments are useful asinitiators for other reactions such as polymerization and crosslinkingas described in copending applications titled Photopolymerization andCrosslinka-ble Polymer Compositions filed concurrently herewith. Theoriginal color of the dye appears when it is treated with acid so thatthe pH of the material is below 7, but no further photobleaching resultswhen the dye is exposed to energy. Each of the fragments produced can beused in various processes, e.g., the aldehyde is an effectivecrosslinking agent as described in the aforementioned application, or asa dye mordant. The free radicals and cations are useful aspolymerization initiators as described in the aforementionedapplication. 1

While certain compounds of this invention are more effective for aparticular utility than others, the preferred ones have one of thefollowing structures:

wherein Q Q Q Q and Q each represent the non-metallic atoms necessary tocomplete a sensitizing or desensitizing nucleus containing 5 or 6 atomsin the heterocyclic ring,

which nucleus can contain at least one additional hetero atom such asoxygen, sulfur, selenium or nitrogen, i.e., a nucleus of the type usedin the production of cyanine dyes, such as the following representativenuclei: a thiazole nucleus, e.g., thiazole, 4-methylthiazole,3-ethylthiazole, 4-phenylthiazole, S-methylthiazole, 5-phenylthiazole,4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl) thiazole,benzothiazole, 4-chlorobenzothiazole, 4- or 5-nitrobenzothiazole,S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-ch1orobenzothiazole,4-methylbenzothiazole, 5 methylbenzothiazole, 6 methylbenzothiazole,6-nitrobenzothiazole, 5 bromobenzothiazole, 6-bromobenzothiazole, 5chloro 6-nitrobenzothiazole, 4-phenylbenzothiazole,4-methoxybenzothiazole, S-methoxybenzothiazole, 6 methoxybenzothiazole,5 iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole,S-ethoxybenzothiazole, a tetrahydrobenzothiazole nucleus, 5,6-dimethoxybenzothiazole, 5,6 methylenedioxybenzothiazole, 5 hydroxybenzothiazole,6-hydroxybenzothiazole, a-naphthothiazole, ,B-naphthothiazole,[3,,B-naphthothiazole, S-methoxy 5,5 naphthothiazole,5-ethoxy-fimaphthothiazole, 8- methoxy or, naphthothiazole, 7methoxy-a-naphthothiazole, 4 methoxythianaphtheno-7,6',4,5-thiazole,nitro group substituted naphthothiazoles, etc.; an oxazole nucleus,e.g., 4-methyloxazole, 4-nitro-oxazole, S-methyloxazole,4-phenyloxazole, 4,5 diphenyloxazole, 4 ethyloxazole,4,5-dimethyloxazole, S-phenyloxazole, benzoxazole, 5 chlorobenzoxazole,5 methylbenzoxazole, 5 phenylbenzoxazole, 5- or 6-nitrobenzoxazole,5-chloro-6-nitrobenzoxazole, 6 methylbenzoxazole,5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole,5- ethoxybenzoxazole, 5-chlorobenzoxazole, 6-meth0xybenzoxazole,S-hydroxybenzoxazole, 6-hydroxybenzoxazole, anaphthoxazole,fl-naphthoxazole, nitro group substituted naphthoxazoles, etc.; aselenazole nucleus, e.g., 4-methylselenazole, 4-nitroselenazole,4-phenylselenazole, benzoselenazole, 5 chlorobenzoselenazole, 5methoxybenzoselenazole, 5 hydroxybenzoselenazole, 5- or 6nitrobenzoselenazole, 5 chloro 6-nitrobenzoselenazole,tetrahydrobenzoselenazole, a naphthoselenazole, p naphthoselenazole,nitro group substituted naphthoselenazoles, etc.; a thiazoline nucleus,e.g., thiazoline, 4-methylthiazoline, etc.; a pyridine nucleus, e.g.,Z-pyridine, S-methyl- 2-pyridine, 4-pyridine, 3-methyl-4-pyridine, nitrogroup substituted pyridines, etc.; a quinoline nucleus, e.g., 2-quinoline, 3-methyl-2-quinoline, S-ethyl-Z-quinoline, 6-chloro-2-quino1ine, 6-nitro-2-quinoline, 8-chloro-2-quinoline,6-methoXy-2-quinoline, S-ethoxy-Z-quinoline, 8-hydroxy-Z-quinoline,4-quinoline, 6-methoxy-4-quinoline, 6- nitro 4 quinoline,7-methy1-4-quinoline, 8-chloro-4- quinoline, l-iso-quinoline,6-nitro-1-isoquinoline, 3,4-dihydro1-isoquinoline, 3-isoquinoline, etc.;a 3,3-dialkylindolenine nucleus, preferably having a nitro or cyanosubstituent, e.g., 3,3-dimethyl-5 or 6-nitroindolenine, 3,3- dimethyl-S-or 6-cyanoindolenine, etc.; and, an imidazole nucleus, e.g., imidazole,l-alkylimidazole, 1-alkyl-4-phenylimidazole,1-alkyl-'4,S-dimethylirnidazole, benzimidazole, 1 alkylbenzimidazole, 1alkyl-S-nitrobenzimidazole, 1- aryl 5,6 dichlorobenzimidazole,l-alkyl-u-naphthimidazole, 1 aryl B-naphthimidazole,1-alkyl-5-methoxy-anaphthimidazole, or, an imidazo[4,5-b]quinoxalinenucleus, e.g., l-alkylimidazo[4,5-b]quinoxaline such as 1- ethylimidazo[4,5-b] -quinoxaline, 6-chlorol-ethylimidazo- [4,5-b1quinoxaline, etc.,l-alkenylimidazo [4,5-b] quinoxaline such as1-allylimidazo[4,5-b]-quinoxaline, 6-ch1oro- 1allylimidazo[4,5-b]quinoxaline, etc., l-arylimidazo- [4,5-b]quinoxalinesuch as l-phenylimidazo[4,5-b]quinoxaline, 6 chloro1-phenylimidazo[4,5-b]quinoxaline, etc.; a 3,3-dialkyl-3H-pyrrolo[2,3-b]pyridine nucleus, e.g., 3,3 dimethyl-3H-pyrrolo[2,3-b]pyridine,3,3-diethyl-3H- pyrr01o[2,3-b] pyridine, etc.; athiaZolo[4,5-b]quino1ine nucleus; an indolyl nucleus includingsubstituted indolyl nuclei such as a 2-phenyl-3 indole,1-methyl-2-phenyl-3- indole; and the like; R represents an alkyl group,including substituted alkyl (preferably a lower alkyl containing from 1to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl butyl, hexyl,cyclohexyl, decyl, dodecyl, etc., and substituted alkyl groups(preferably a substituted lower alkyl containing from 1 to 4 carbonatoms), such as a hydroxyalkyl group, e.g., fi-hydroxyethyl,w-hydroxybutyl, etc., an alkoxyalkyl group, e.g., B-methoxyethyl,wbutoxybutyl, etc., a carboxyalkyl group, e.g. p-carboxyethyl,w-carboxybutyl, etc., an alkoxy group, e.g., methoxy, ethoxy, etc. asulfoalkyl group, e.g., fl-sulfoethyl, w-sulfobutyl, etc., asulfatoalkyl group, e.g., fi-sulfatoethyl, wsulfatobutyl, etc., anacyloxyalkyl group, e.g., fl-acetoxyethyl, 'y-acetoxypropyl,w-butyryloxybutyl, etc., an alkoxycarbonylalkyl group, e.g.,p-methoxycarbonylethyl, wethoxycarbonylbutyl, etc. or an aralkyl group,e.g., benzyl, phenethyl, etc.; an alkenyl group, e.g., allyl,l-propenyl, 2-butenyl, etc., or an aryl group, e.g., phenyl, tolyl,naphthyl, methoxyphenyl, chlorophenyl, etc.; Q represents thenon-metallic atoms required to complete a 5 to 6 membered heterocyclicnucleus, typically containing a hetero atom selected from nitrogen,sulfur, selenium, and oxygen, such as a 2-pyrazolin-5-one nucleus (e.g.,3- methyl 1 phenyl 2-pyrazolin-5-one, 1-pheny1-2-pyrazolin-S-one, 1 (2benzothiazolyl) 3-methyl-2-pyrazolin-S-one, etc.); an isoxazolonenucleus (e.g., 3-phenyl 5 (4H) isoxazolone, 3-methyl-5-(4H)-isoxazolone,3- methyl 5 (4H)-isoxazolone, etc.); an oxindole nucleus (e.g.,1-alkyl-2,3-dihydro-2-oxindoles, etc.), a2,4,6-triketohexahydropyrimidine nucleus (e.g., barbituric acid or2-thiobarbituric acid as well as their l-alkyl (e.g., 1- methyl,l-ethyl, l-propyl, l-heptyl, etc.) or 1,3-dialkyl (e.g., 1,3 dimethyl,1,3 diethyl, 1,3-dipropyl, 1,3-diisopropyl, 1,3 dicyclohexyl, 1,3di(fi-methoxyethyl), etc.) or 1,3-diaryl (e.g., 1,3-diphenyl,1,3-di(p-chlorophenyl), 1,3 di(p-ethoxycarbonylphenyl), etc.) or l-aryl(e.g., 1- phenyl, l-p-chlorophenyl, l-p-ethoxycarbonylphenyl), etc.) orl-alkyl-S-aryl (e.g., 1-ethyl-3-phenyl, l-n-heptyl- 3-phenyl, etc.derivatives), a rhodanine nucleus (i.e., 2- thio-2,4-thiazolidinedioneseries), such as rhodanine, 3- alkylrhodanines (e.g., 3-ethylrhodanine,3-allylrhodanine, etc.), 3-carboxyalkylrhodanines (e.g.,S-(Z-carboxyethyD- rhodanine, 3 (4-carboxybutyl)rhodanine, etc.),3-sulfoalkylrhodanines (e.g., 3-(2-sulfoethyl)rhodanine, 3-(3-sulfopropyl)rhodanine, 3 (4-sulfobutyl)rhodani11e, etc.), or3-arylrhodanines (e.g., B-phenylrhodanine, etc.), etc.; a2(3H)-imidazo[1,2-a]-pyridone nucleus; a Z-furanone nucleus (e.g.,3-cyano-4-phenyl-2(5H)-furanone); a thiophen-3-one-l,1-dioxide nucleus(e.g., benzo[b]thiophen- 3(2H) one-1,1-dioxide); a5,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]-pyrimidine nucleus (e.g.,5,7-dioxo-3- phenyl 6,7 dihydro-S-thiazolo[3,2-a]pyrimidine, etc.); a 2-thio-2,4-oxazolidinedione nucleus (i.e., those of the 2-thio-2,4-(3H,5H)-oxazoledione series) (e.g., 3-ethyl-2-thio- 2,4oxazolidinedione, 3-(2-sulfoethyl)-2-thio-2,4-oxazolidinedione, 3(4-sulfobutyl)-2-thio-2,4-oxazolidinedione, 3 (3carboxypropyl)-2-thio-2,4-oxazolidinedione, etc.); a thianaphthenonenucleus (e.g., 2-(2H)-thianaphthenone, etc.); a2-thio-2,5-thiazolidinedione nucleus (i.e., the 2- thio 2,5 3H,4H)thiazoledione series) (e.g., 3-ethyl-2- thio-2,S-thiazolidinedione,etc.); a 2,4-thiazolidinedione nucleus (e.g., 2,4-thiazolidinedione,3-ethyl-2,4-thiazolidinedione, 3 phenyl-2,4-thiazolidinedione,3-a-naphthyl- 2,4 thiazolidinedione, etc.); a thiazolidinone nucleus(e.g., 4-thiazolidinone, 3-ethyl-4-thazolidinone, 3-phenyl-4-thiazolidinone, 3-a-naphthyl-4-thiazolidinone, etc.), a 2-thiazoline-4-one series (e.g., Z-ethylmercapto-Z-thiazolin- 4-one,2-alkylphenylamino-2-thiazolin-4-one, 2-diphenylamino-2-thiazolin-4-one,etc.); a 2-imino-4-oxazolidinone (i.e., pseudohydantoin) nucleus; a2,4-imidazolidinedione (hydantoin) series (e.g., 2,4-imidazolidinedione,3-ethyl- 2,4 -imidazo1idinedione, 3-phenyl-2,4-imidazolidinedione, 3 anaphthyl-2,4-imidazolidinedioue, 1,3-diethyl-2,4- imidazolidinedione, 1ethyl 3phenyl-2,4-imidazolidinedione, 1 ethyl2-a-naphthyl-2,4-imidazolidinedione,1,3-diphenyl-2,4-imidazolidinedione, etc.), a 2-thio-2,4-imidazolidinedione (i.e., 2-thiohydantoin) nucleus (e.g.,

8 2-thio-2,4-imidazolidinedione, 3 ethyl 2-thio-2,4-imidazolidinedione,3 (4 sulfobutyl)-2-thio-2,4-imidazolidinedione, 3(Z-carboxyethyl)-2-thio-2,4-imidazolidinedione, 3 phenyl2-thio-2,4-imidazolidiuedione, 3-anaphthyl 2thio-2,4-imidazolidinedione, 1,3-diethyl-2- thio 2,4 imidazolidinedione,l-ethyl-3-phenyl-2-thi0-2,4- imidazolidinedione, 1 ethyl 3--naphthyl-2-thio-2,4- imidazolidinedione, 1,3 diphenyl2-thio-2,4-imidazolidinedione, etc.), a Z-imidazolin-S-one nucleus(e.g., 2- propylmercapto-2-imidazol-iu-5-one, etc.)

n is a positive integer from 1 to 4; m is a positive integer from 1 to3; g is a positive integer from 1 to 2;

R and R each represent a cyano radical, an ester radical such asethoxycarbonyl, methoxycarbonyl, etc., or an alkylsulfonyl radical suchas ethylsulfonyl, methylsulfonyl, etc.;

L represents a methine linkage having the formula wherein T is hydrogen,lower alkyl of 1 to 4 carbon atoms or aryl such as phenyl, e.g., CH=,C(CH C(C6H5)=, etc.;

D, E, J, R and R each represent a hydrogen atom, an alkyl group(preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g.,methyl, ethyl, propyl, isopropyl, butyl, decyl, dodecyl, etc., or anaryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl,nitrophenyl, etc.;

X represents an acid anion, e.g., chloride, bromide, iodide,perchlorate, tetrafluoroborate, sulfamate, thiocyanate,p-toluenesulfonate; methyl sulfate, etc.;

G represents an anilino radical or an aryl radical, e.g., phenyl,naphthyl, dialkylaminophenyl, tolyl, chlorophenyl, nitrophenyl,anilinovinyl, etc.;

R is an alkyleneoxy radical having 1 to 8 carbon atoms in the alkylenechain including an alkylenedioxy radical and an arylenebisalkoxy radicale.g., ethyleneoxy, trimethyleneoxy, tetramethyleneoxy, propylideneoxy,ethylenedioxy, phenylenebisethoxy, etc.;

R represents either (1) an alkyl radical including a substituted alkyl(preferably a lower alkyl having 1 to 4 carbon atoms), e.g., methyl,ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl,aralkyl such as benzyl, sulfoalkyl such as fi-sulfoethyl, w-sulfobutyl,wsulfopropyl; or (2) an acyl radical, e.g.,

wherein R is an alkyl including a substituted alkyl or an aryl radicalsuch as methyl, phenyl, naphthyl, propyl, benzyl, etc.

In the above formulae Q preferably completes a pyridine, an indole or aquinoline nucleus. Also, D, E and J are preferably aryl radicals. Nucleiwherein Q Q Q Q and Q complete an imidazo [4,5-b]quinoxaline nucleus, ora nitro group thiazole, oxazole, selenazole, thiazoline, pyridine,quinoline, indole, or imidazole nucleus are referred to hereafter asdesensitizing nuclei.

Typical compounds and intermediates included in the scope of thisinvention are the following:

1. 3-ethyl-1-methoxyoxa-2'-pyridocarbocyanine perchlorate 2.1'-ethoxy-3-ethyloxa-2-pyridocarbocyanine tetrafiuoroborate 3.3-ethy1-1-methoxy-2-pyridothiacyanine iodide 4.1-ethoXy-3'-ethyl-2-pyridothiacyanine tetrafluoroborate 5.1-benzyloxy-3'-ethyl-2-pyridothiacyanine iodide 6.3'-ethyl-1-methoxy-Z-pyridothiacarbocyanine iodide 7.1-ethoxy-3'-ethyl-Z-pyridothiacarbocyanine tetrafiuoroborate 8.anhydro-3 '-ethyl-1-(3-sulfopropoxy)-2-pyridothiacarbocyanine hydroxide9. 1-benzyloxy-3-ethyl-2'-pyridothiacarbocyanine perchlorate 10.3'-ethyl-1-methoxy-2-pyridothiacarbocyanine perchlorate 11.1-meth0xy-1,3,3-trimethylindo-2'-pyridocarbocyanine picrate 12.3-ethyl-1-methoxy-4,5'-benzo-2-pyridothiacarbocyanine perchlorate 13.1-ethoxy-3'-ethyl-4,5-benzo-2-pyridothiacarbocyanine tetrafluoroborate14. 1'-ethoxy-3-ethyloxa-2-carbocyanine tetrafluoroborate 15.1'-ethoxy-3-ethylthia-2'-cyanine tetrafiuoroborate 16.1'-ethoxy-3-ethylthia-2'-carbocyanine tetrafluoroborate 17.1-ethoxy-3-ethylthia-2-dicarbocyanine tetrafiuoroborate 18.1-methoxy-3'-methyl-2-pyridothiazolinocarbocyanine perchlorate 19.3'-ethyl-1methoxy-4-pyridothiacyanine perchlorate 20.3-ethyl-1-methoxy-4-pyridothiacarbocyanine perchlorate 21.1,1-dimethoxy-2,2'-diphenyl-3,3'-indolocarbocyanine perchlorate 22.l-methoxy-1'-methyl-2,2',10-triphenyl-3,3'-indolocarbocyanineperchlorate 23. 1,1'diethoxy-2,2-diphenyl-3,3'-indolocarbocyanineperchlorate 24.1-ethoxy-1'-methyl-2,2',10-triphenyl-3,3-indolocarbocyanine perchlorate25. 1'-ethoxy-3-ethyl-4,5-benzothia-2-carbocyanine tetrafluoroborate 26.2-B-anilinovinyl-l-methoxypyridinium p-toluenesulfonate 27.l-ethyl-1'-methoxy-4,S-benzothia-4-carbocyanine perchlorate 28.3-ethyl-1-methoxy-6-nitro-2-phenyl-3-indolothiacarbocyaninep-toluenesulfonate 29.1-ethoxy-3'-ethyl-6-nitro-2-phenyl-3-indolothiacarbocyaninep-toluenesulfonate 30. 1,3-diallyl-l-methoxy-2'-phenylimidazo[4,5-b]-quinoxalino-3'-indolocarbocyanine perchlorate 3 1.1,3-diallyl-1'-ethoxy-2-phenylimidazo [4,5-b]-quinoxalino-3'-indolocarbocy-anine perchlorate 32.1-methoXy-Z-methyIpyridinium p-toluenesulfonate 33.1-methoXy-4-methylpyridinium p-toluenesulfonate 34.anhydro-Z-methyl-1(3-sulfopropoxy)pyridinium hydroxide 35.1-ethoxy-2-methylpyridinium tetrafiuoroborate 36.1-benzyloxy-Z-methylpyridinium bromide 37. 1-ethoxy-2-methylquinoliniumtetrafiuoroborate 38. 1-methoxy-2-phenylindole 39.I-ethoxy-Z-phenylindole 40.1-methoxy-1,3,3-trimethyl-5-nitro-2'-phenylindo- 3'-indolocarbocyanineperchlorate 41. 1-methoxy-1',3',3'-trimethyl-2-phenyl-3-indolo-2-pyrrolo[2,3-b]pyridocarbocyanine perchlorate 42.1'-ethoxy-l,3,3-trimethyl5-nitro-2'-phenylindo- 3'-indolocarbocyaninep-toluenesulfonate 43.1-ethoxy-1,3',3-trimethyl-2-phenyl-3-indolopyrrolo-[2,3-b]pyridocarbocyanine perchlorate 44.1,1'-ethylenedioxybispyridinium dibromide 45.1,l'-trimethylenedioxybispyridiniurn dibromide 46.1,1'-tetramethylenedioxybis(Z-methylpyridinium)- dibromide 47.1,1-tetramethylenedioxybis(4-methylpyridinium)- dibromide 48.1,1-tetramethylenedioxybispyridinium dibromide 49.1,1'-pentamethlenedioxybispyridinium dibromide 50.1-methoxy-2-phenylindole-3-carboxaldehyde The novel compounds of thisinvention are prepared by various methods. The following examplesdemonstrate some of the techniques that can be used. Indicated meltingpoints are C.

EXAMPLE 1 Preparation of Compound 32 (Method A) A mixture of2-picoline-N-oxide (10.9 g., 0.1 mole) and methyl p-toulenesulfonate(27.9 g., 0.1 mole+50%) is heated on a steam bath, with constantstirring, until an exothermic reaction starts. The heating is stoppedand the temperature rises to a maximum of about The mixture is allowedto cool, diluted to 200 ml. with acetone and chilled. The solid whichseparates is collected and washed with acetone. The yield is 23.2 g.(79%), mp. 1134 C.

EXAMPLE 2 Preparation of Compound 36 (Method B) 2-Picoline-N-oxide (10.9g., 0.1 mole) and benzyl bromide (18.8 g., 0.1 mole+10%) are dissolvedin acetone (25 ml.) and the mixture is heated at reflux for 10 minutes.After dilution to ml. with acetone, the mixture is allowed to cool. Thesolid preciptate is collected and washed with acetone. The yield is 19.0g. (68%), mp. 1134.

EXAMPLE 3 Preparation of Compound 26 Compound 32 (5.90 g., 0.02 mole)and ethyl isoformanilide (2.98 g., 0.02 mole) in dimethyl formamide (5ml.) are heated on a steam bath for /2 hour. The mixture is diluted withacetone (50 ml.) and chilled. The yellow solid which separates iscollected and washed with acetone. The yield is 3.3 g. (41%), mp.172-3".

EXAMPLE 4 Preparation of Compound 13-Ethyl-1'-methoxyoxa-2'-pyridocarbocyanine perchlorate 0 L CH=CHCHJ N6MB 010.- N/

l-Methoxy 2 methylpyridinium p toluenesulfonate (2.22 g., 1 mol.-+50%),2-18-acetanilidovinyl- 3 ethylbenzoxazolium iodide (2.17 g., 1 mol.) andtrirnethylamine (1.41 ml., 1 mol.+100%) in ethanol (20 ml.) are heatedat reflux for 2 minutes. Then a solution of sodium perchlorate (0.61 g.,1 mol.) in hot methanol is added. After chilling, the solid is collectedand washed with ethanol. Yield 1.50 g. (77%), m.p. 146-7".

11 EXAMPLE Preparation of Compound 33'-Ethyl-1-methoxy-Z-pyridothiacyanine iodide Preparation of Compound 63-Ethyl-1-methoxy-2-pyridothiacarbocyanine iodide l-Methoxy 2methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50%),Z-fi-acetanilidovinyl 3 ethylbenzothiazolium iodide (2.25 g., 1 mol.)and triethylamine (1.4 ml., 1 mol.+100%) in ethanol ml.) are heated atreflux for 2 minutes. The mixture is chilled and the solid whichseparates is collected and washed with ethanol. Yield 1.27 g. (58%),m.p. 115.

EXAMPLE 7 Preparation of Compound 103'-Ethyl-1-methoxy-2-pyridothiadicarbocyanine perchlorate CH=CHCH=CHCH=I OMe N Preparation of Com-pound 111'-Methoxy-1,3,3-trimethylindo-2'-pyridocarbocyanine picrate OzN NO:

I NC:

1-Methoxy 2 methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50%),Z-fi-acetanilidovinyl 1,3,3 trimethyl-3H-indolium iodide (2.23 g., 1mol.), triethylamine (1.4 ml., 1 mo1.+%) in ethanol (20 m1.) are heatedat reflux for 2 minutes. The solution is cooled and a solution of picricacid (1.15 g., 1 mol.) in ethanol added. After chilling, the solid iscollected and washed with ethanol. Yield 1.12 g. (40%).

EXAMPLE 9 Preparation of Compound 123'-Ethy1-1-methoxy-4',5'-benzo-2-pyridothia carbocyanine perchloratl-Methoxy 2 methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50%2-,B-auilinovinyl-l-ethylnaphtho- [1,2-d]thiazolium p-toluenesulfonate(2.57 g., 1 mol.) and triethylamine (1.4 ml., 1 mol.+100%) in aceticanhydride (25 ml.) are warmed to 40 and stirred for 5 minutes. The smallamount of undissolved solid is removed by filtration and the filtratediluted with excess ether. The othe layer is decanted and the residuedissolved in methanol (25 ml.). A solution of sodium perchlorate (0.61g., 1 mol.) in methanol is added. After chilling, th solid is collectedand washed with methanol. Yield 1.48 g. (65%), m.p. indistinct.

EXAMPLE 10 Preparation of Compound 211,1'-Dimethoxy-2,2'-diphenyl3,3'-indolocarbocyanine perchlorate EXAMPLE11 Preparation of Compound 22 l-Methoxy-'-methyl-2,2',10-triphenyl-3,3'-indol0- carbocyanine perchlorate3-Formyl-1-methoxy-2-phenylindole (1.26 g., 1 mol.) and1-methyl-2-methylenebenzyl-2-phenylindole (1.55 g., 1 mol.) aredissolved in hot acetic acid (10 ml.). 60% HClO (1.0 ml.) in acetic acid(3 ml.) is added and the mixture allowed to cool. After two hours atroom temperature, the solid is collected and Washed with methanol andether. After recrystallization from methanol acidified with I-IClO theyield of purified dye is 1.92 g. (59% m.p. 2589 C.

EXAMPLE 12 Preparation of Compound 283-Ethyl-1-methoxy-6-nitro-2-phenyl-3-indolothiacarbocyaninep-toluenesulfonate 3-Formyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.),3-ethyl-2-methyl-6-nitrobenzothiazolium p toluenesulfonate (1.98 g., 1mol.) and acetic anhydride (10 ml.) are heated at reflux for 1 minute.After cooling, excess ether is added slowly. The solid is collected andwashed with ether. After recrystallization from methanol acidified withp-toluenesulfonic acid, the yield of purified dye is 2.64 g. (84%).

EXAMPLE 13 Preparation of Compound 30 1,3-Dia1lyl-1'-methoxy-2-phenylimidazo [4, -b] -quinoxalino3'-indolocarbocyanine perchlorate CHzCH=CH2 This dye is prepared in themanner described in Example 31, except that1,3-diallyl-2-methylimidazo[4,5-b] quinoxalinium p-toluenesulfonate(2.18 g., 1 mol.) is used in place of3-ethyl-2-methyl-G-nitrobenzothiazolium ptoluenesulfonate. Afterrecrystallization from a mixture of acetonitrile (65 ml.) and 60% HClO(1.0 ml.), the yield of purified dye is 1.78 g. (60% m.p. 229-3l C.

EXAMPLE 14 Preparation of Compound 38 l-Methoxy-Z-phenylindole Sodium(3.0 g., 1 mol. l 30%) is dissolved in methanol (200 ml.).1-Hydroxy-2-phenylindole (20.9 g., 1 mol.) [Fischer, Ber. 28; 585 (1895)and Ber. 29, 20.63 (1896)] and methyl iodide (25.6 g., 1 mol. 80%) areadded, and the mixture refluxed for 1 hour. The solution is chilled, andthe solid which separates is collected and washed with methanol. Yield15.9% g. (71%), m.p. 5l2 C.

EXAMPLE 15 Preparation of Compound 40 1-Methoxy-1,3,3-trimethy1-5-nitro-2'-phenylindo- 3'-indolocarbocyanine perchlorate Me Ma Q H No:Me() N CH=C W. Ph

Me C104- 3-Formyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.),l,2,3,3-tetramethyl 5-nitro-3H indolium p-toluenesulfonate (1.30 g., 1mol.) and acetic anhydride (10 ml.) are heated at reflux for 1 minute.After cooling, excess ether is added. The ether layer is decanted, theviscous residue dissolved in methanol (25 ml.) and 60% HClO (1.0 ml.) inMeOH (5 ml.) added. The mixture is chilled and the solid collected andwashed with methanol. After recrystallization from a mixture of methanoland acetonitrile, the yield of purified dye is 1.20 g. (43%), m.p. 266C.

EXAMPLE 16 Preparation of Compound 41 l-Methoxy-l 3 3'-trimethyl-2-phenyl-3-indolo-2- pyrrolo[2,3-b] pyridocarbocyanineperchlorate Me Me Q MeON CH=CH g A Me 0104-3-Forrnyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.),1,3,3-trimethyl-2-methylene 2,3-dihydropyrrolo[2,3-b] pyridine (0.87 g.,1 mol.), p-toluenesulfonic acid monohydrate (0.95 g., 1 mol.) and aceticanhydride (10 ml.) are heated at reflux for 1 minute. The mixture isallowed to cool, diluted with ether, and the ether layer decanted. Theresidue is dissolved in methanol (25 ml.) and 60% HClO (1.0 ml.) in 5ml. methanol added. After chilling, the solid is collected and Washedwith methanol. After one recrystallization from acetonitrile, the yieldof purified dye is 1.78 g. (69%), m.p. 235-9" C.

EXAMPLE 17 Preparation of Compound 50 3-Formyl-l-methoxy-Z-phenylindolePhosphoryl chloride (5.2 ml., 1 mol. 10%) is added slowly to dimethylformamide (15 ml.), with cooling, so that the temperature does notexceed 20. A solution of l-methoxy-Z-phenylindole (11.15 g., 1 mol.) indimethyl formamide (30 ml.) is added slowly, while keeping thetemperature below 25 The mixture is warmed at 40 for 45 minutes, thenpoured into ice water (390 ml). 5N NaOH (70 ml.) is added, and a viscousmass separated. The mixture is heated to 65 and the lumps broken up. Thesolid is collected and washed with water. The yield is 11.95 g. (96%),m.p. 116-7", unchanged after recrystallization from ethanol.

The same general methods of preparation set forth in Examples 1-17 areused for the synthesis of additional compounds. The compound prepared,method, solvent, yield and melting points for these compounds are setforth in the following tables.

TABLE I Melting Yield point, Solvent (percent) degrees 43 Decomposes. 33Do. 18 125-30. 89 Deeomposes. 45 128-31. 45 125. 81 Deeomposes. 38 143.47 Decomposes. 63 138-9. 35 127-8. 20 186-7. 58 128. 36 219-21. 55205-9. 40 Decomposes. 100 D0. 13 58 220-1. 15 (no NaOl added). 65194-200 16 dO 69 237-41 1 Reaction mixture diluted with acetone toprecipitate dye. Reaction temperature 25, no NaClOi added.

TABLE II Melting Cpd. Yield point, N 0. Base Alkylating agent MethodSolvent (percent) degrees 33 4picoline-N0xide Methyl p-toluenesulfonateA 97 153-4 34 Z-picoline-N-oxide. 1,3-propanesultone B 95 202-3 35 ..doTriethyloxonium tetrafluoroborate. B 80 53-7 37 Quinaldine-N-oxide ..doB 90 115-7 39 1-hydroxy-2-phenylindol- Ethyl iodide Ex. 14 100 Oil 44Pyridine-N-oxide 1,2-dibromoethane.... A 81 170-1 45 do1,3-dibromopr0pane A 100 151-3 46 2-picoline-N-0xide-..1,4-dibromobutane A 88 153-4 47 4-picoline-N-oxide d B 39 109-11 48Pyridine-N-oxirle do A 91 172 49 do 'bromopen no A 33 115-7 511-ethoxy-2-phenylind Ex. 17 98 95-6 EXAMPLE 50 they receive. Thebleaching results from the fragmenta- 1,3-Diethyl--[ 1-methoxy-2( 1H-pyridylidene ethylidene]-2-thiobarituric acid [1 C) Et N CH-CH- =S N--N Me Z-B-anilinovinyl-l-methoxypyridinium p toluenesulfonate (3.99 g.,1 mol.) 1,3-diethyl-2-thiobarituric acid (2.00 g., 1 mol.) and aceticanhydride ml.) are stirred together as triethylamine (5 ml.) is added.The mixture is stirred for a few minutes until all the solid isdissolved. A seed crystal is added [obtained by dilution of a smallportion of reaction mixture with excess ether] and the mixture chilled afew hours. The solid dye is collected and washed, first with methanol,then with ether. The yield of dye is 1.48 g. (44%), mp. 171-2 dec.

The following compounds are prepared in the same manner as compound 54is Example 50. The compound prepared, yield and melting points are setforth in Table III below.

TABLE III Melting Cpd. Yield poin Ex. No. No. (percent) C.)

51 55 47 75.5. 52--. 56 154-5. 53.-- 57 73 Decomposes. 54 58 79 169-70.55 59 88 1,334.

In order to provide a better understanding of the many facets of theinvention, several applications will be discussed in detail. While thenovel compounds described hereinbefore are useful in the variousembodiments set forth below, preferred ones are described.

tion of the dye molecule, fragmentation being caused, at least in part,by the cleavage of the NO linkage. Thus, when the dyes are coated on orimbibed into a suitable support and exposed in an imagewise manner,direct positive reproductions are obtained. The advantages of thisprocess are numerous, e.g., no chemical development is necessary nor isthere any need for any other material in the coating composition otherthan the dye itself. Since the dyes of the invention are of differentcolors, images having various colors can be made. For coating purposes,it is often convenient to disperse the dye in a film-forming binder.Useful binders include those which are commonly used in preparingphotographic elements.

While generally all of the compounds encompassed by formulae A through Hare suitable in preparing photobleach images, the preferred ones havethe following structure:

17 wherein:

R, R R R R L, Q Q X, G, n, g and m are each defined above. Typicalcompounds exemplary of the above include compounds 1-13, 18, 26, 52through 59.

Since these bleachable dyes are of various colors, as explainedpreviously, they can be used in the production of direct positive colorprints. Thus, when a white substrate is coated with a layer of a yellowdye, a layer of a magenta dye and a layer of a cyan dye and theresultant element is exposed to White light through a colortransparency, a direct positive color print is obtained. The three dyesneed not be present as separate layers but may be in a uniformadmixture. The color image is obtained by virtue of the fact that thesedyes are bleached when exposed to a light source of substantially thesame wavelength which they absorb. Since yellow absorbs blue, wherelight in the blue region strikes the yellow layer, the yellow layerbleaches and becomes colorless. .Si-milar effects are observed in theother two layers, magenta absorbing green and bleaching and cyanabsorbing red and bleaching in proportions to the exposure received. Theresult of the process is a right-reading color reproduction of the colororiginal. Such a process is generally known in the art, and is morefully described in US. 3,104,973 (Sprague et al.).

EXAMPLE 56 A solution of 46.1 mg. of compound 12 (magenta), 43.7 mg. ofcompound (cyan) and 39.8 mg. of compound 4 (yellow) in 50 g. of 20%poly-(2-vinylpyridine) binder is prepared by rotary mixing. After twohours mixing 1.46 g. of triethanolamine is added and the solution ismixed for an additional two hours. The solution is then coated on awhite pigmented cellulose acetate base at a thickness of 0.002 in. Afterdrying, the elements are exposed through a color positive transparencywith a high intensity flash lamp. Instant color positives are obtained.

THERMOGRAPHIC COPYING The dyes of the invention (i.e., formulae A-H) canbe used to prepare thermographic copy elements. As explained previously,the compounds of this invention fragment when subjected to various formsof energy. Accordingly, when these compounds are exposed to heat,fragmentation occurs. The compounds lose their original color andgenerally are bleached. Because of this feature, they can be used inthermographic copy sheets as the heat-sensitive material. Dyes offormula E are preferred.

The compounds forming the heat-sensitive areas of a copy sheet can becoated on or imbibed into any suitable support (especially supportshaving low thermal conductivity). In general, ordinary paper can be usedas a support for the heaflsensitive composition and the paper can betransparent, translucent or opaque. It is frequently desirable to use asupport which transmits the exposing radiation, especially where theoriginal does not transmit such radiation (i.e., at least one of theseshould transmit such radiation). Advantageously, a paper or otherfibrous material can be employed which has a charn'ng temperature aboveabout 125 C.

In preparing thermographic elements of this invention, theheat-sensitive dye is usually coated on a translucent or opaque support.After a period of drying, the heat-sensitive, copying sheet can then beplaced in contact with an original containing line copy, such astypewritten characters, and exposed to infrared radiation. The portionsof the original which are highly absorptive of the infrared radiationconvert the radiation to heat which is conducted to the copying materialproducing a rapid color change in those portions of the copying sheetwhich are in heat-conductive relationship with the original. Theportions of the copying sheet which are not in heat-conductiverelationship with the original, transmit or reflect the infraredradiation so that no color change occurs.

If desired, the heat-sensitive compounds of the invention can bedispersed in a binding material and the entire composition coated on thesurface of the support. Suitable binding agents include ethyl cellulose,polyvinyl alcohol, gelatin, collodion, polyvinyl acetal, celluloseesters, hydrolyzed cellulose esters, etc. When a colloidal binding agentis employed, the amount thereof used can be varied in order to vary thecontrast of the resulting copy. These effects are well understood bythose skilled in the art. Various esthetic effects may be produced byadding inert pigments or colorants to the colloidal dispersions,although there is generally no advantage to be gained by the use of suchmaterials. In some instances, an apparent increase in contrast can beobtained by using a coloring pigment in the colloidal binding material.

The source of infrared radiation can be arranged so that the rearsurface of the original receives the infrared radiation, although insuch cases it may be convenient to have an insulating surface applied tothe rear surface of the original in order to localize and intensify theheat received by the original. Alternatively, the heat-sensitive layerof the copying material can be placed in contact with the printedcharacters of the original and the assembly then exposed either from therear side of the original or the rear side of the copying sheet. Theseadaptations are well understood by those skilled in the art and areillustrated in domestic and foreign patents. See for example, Miller US.Pat. 2,663,657, issued Dec. 22, 1953.

Exposure of the thermographic element can be accomplished by reflex (asexplained above) or by bireflex techniques. According to the lattermethod, a support for such an exposure should be readily permeable toradiant energy, such as infrared radiation. Also, the support isadvantageously relatively thin so that the heat generated in the printedcharacters of the original can be transmitted to the heat-sensitivelayer thereby causing a color change to take place in a patterncorresponding to the printed characters. If desired, the support can beordinary paper which has been transparentized temporarily, so thatexposure can be made as described. The transparentizing substance canthen be removed after exposure to provide an opaque reflecting support.Such transparentizing treatment is well known to those skilled in theart.

It has also been found that the application of the heatsensitive layerto the support need not be done in a uniform manner, but that theheat-sensitive layer can be applied non-uniformly in a regular pattern,such as lines or dots. Such coatings can be used for special purposes,such as in the graphic arts field.

While only an infrared lamp has been discussed as the exposing source,it is to be understood that other sources of radiant energy canconveniently be employed in the described thermographic process.Advantageously, the source of radiation is selected so that it isstrongly absorbed by the characters or printed materials beingreproduced. Thus, the characters absorb the radiant energy and transformit into heat which is transmitted to the heatsensitive coating.Incandescent bodies can conveniently be employed as the source ofradiant energy, since such incandescent material is generally rich inthe radiant energy absorbed by many of the printing materials currentlybeing used. Where the radiant energy is not transmitted by the supportbearing the heat-sensitive material, the material being copied shouldtransmit such radiant energy so that exposure can be made through therear surface of the material bearing the printed characters.

While any of the compounds within the scope of formulae A-H are operablein the novel heat-sensitive elements described herein, compounds 1-53are preferred.

EXAMPLE 57 A paper support is coated with a layer of a compositioncontaining gelatin and compound 12. A graphic original having printedmaterial thereon is placed in contact with the uncoated surface of thepaper. Upon exposure of the assembly to infrared radiation supplied byan infrared lamp, a fascimile copy of the printed characters of theprinted characters of the original is obtained.

EXAMPLE 8 A composition containing compound 32 in gelatin is coated onan aluminum base. The element is written on with a hot stylus on thenoncoated side. A good image is recorded in the heated areas.

LIGHT-SCREENING LAYERS The dyes described herein have been found to beuseful in light-screening layers, including antihalation and filterlayers, in photographic light-sensitive elements employing one or moresensitive silver halide layers. They can be incorporated readily incolloidal binders used for forming such layers or they can be coatedwithout the aid of a vehicle. They are especially useful in gelatinlayers adjacent to the silver halide layers and also in dry processes.The dyes can be readily bleached without the need for removing thelayers containing them. Bleaching of the dyes occurs when the layercontaining them is subjected to some form of energy, e.g., light orheat. The energy causes the compound to fragment and become colorless,as explained previously.

These dye compounds can be mordanted in layers coated in contact withlight-sensitive silver halide emulsion layers since the mordanted dyeshave very good stability at the pH of most sensitive silver halideemulsions and have little or no undesirable effect on the silver halide.Also, the dyes can be used as light-screening dyes in layers coateddirectly on top of sensitive silver halide emulsion layers or betweentwo sensitive silver halide emulsion layers or between the support and asensitive silver halide emulsion layer or on the back of the support asan anti halation layer. The elements in which these materials are usedas screening layers can contain either the conventional developing-outsilver halide emulsions or light-developable silver halide emulsionssuch as those described in Ser. No. 481,918, filed Aug. 23, 1965, nowU.S. Pat. No. 3,418,122 and Ser. No. 625,590, filed Mar. 24, 1967, nowU.S. Pat. No. 3,447,927.

The light-screening layers of this invention are prepared by coating onthe photographic element or on its support, by methods well known in theart, a solution of the dye, a hydrophilic colloid binder and a coatingaid such as saponin. In addition to these materials, it is advantageousto add a mor'dant to this solution to render the dye nonwandering. Formost purposes it is desirable to add agents to harden the colloidalbinder material so that the lightscreening layer will remain intact inthe photographic element during and following the processing operation.The pH of the coating solution is adjusted when necessary to a levelthat is compatible with the light-sensitive emulsion layer by the usualmethods.

The proportions of the dye, colloidal binder, mordant, hardener, andcoating aid used in making the light-screening layers can be varied overwide ranges and will depend upon the specific requirements of thephotographic element being produced. The methods used to determine theoptimum composition are well known in the art and need not be describedhere.

The light-sensitive layer or layers and the light-screening layer orlayers of the photographic element can be coated on any suitable supportmaterial used in photography such as cellulose nitrate, celluloseacetate, synthetic resins, paper, metal, glass, etc.

Hydrophilic colloidal materials used as binders for light-screening dyesof the invention include gelatin, collodion, of carboxylated cellulose,hydroxy ethyl cellulose, carboxy methyl cellulose, carboxmethylhydroxyethyl cellulose, synthetic resins, such as the amphotericcopolymers described by Clavier et al. in U.S. Pat. 2,949,442, issuedAug. 16, 1960, polyvinyl alcohol, and others well known in the art. Theabove mentioned amphoteric copolymers are made by polymerizing a monomerhaving the formula:

CHQZCR OOH wherein R represents an atom of hydrogen or a methyl group,and a salt of a compound having the general formula:

CH=CR CHzNHz wherein R has the above mentioned meaning, such as anallylamine salt. These monomers can further be polymerized with a thirdunsaturated monomer in an amount of 0 to 20% of the total monomer used,such as an ethylene monomer that is copolymerizable with the twoprincipal monomers. The third monomer can contain neither a basic groupnor an acid group and may, for example, be vinyl acetate, vinylchloride, acrylonitrile, methacrylonitrile, styrene, acrylates,methacrylates, acrylamide, methacrylamide, etc. Examples of thesepolymeric gelatin substitutes are copolymers of allylamine andmethacrylic acid; copolymers of allylamide, acrylic acid and acrylamide;hydrolyzed copolymers of allylamine, methacrylic acid and vinyl acetate;copolymers of allylamine, acrylic acid and styrene; the copolymer ofallylamide, methacrylic acid and acrylonitrile; etc.

In preparing the light-screening layer composition, the dye is generallyadded to the water-permeable colloidal binder in water solution. In someinstances it can be advantageous to form an alkali metal salt of the dyeby dissolving the dye in a dilute aqueous alkali metal carbonatesolution. Usually a coating aid, such as saponin is added to the dyecolloidal suspension before coating it as a layer on the photographicelement. The dye is advantageously mordanted with a suitable basicmordant added to the colloidal suspension before coating.

Mordants that can be used include the mordants described by Minsk inU.S. 2,882,156, issued Apr. 14, 1959, prepared by condensing apolyvinyl-oxo-compound such as a polyacrolein, a poly-'y-methylacrolein,a polyvinyl alkyl ketone such as polyvinyl methyl ketone, polyvinylethyl ketone, polyvinyl propyl ketone, polyvinyl butyl ketone, etc., orcertain copolymers containing acrolein, methacrolein, or the abovementioned vinyl alkyl ketone components, for example, 1 to 1 molar ratiocopolymers of these components with styrene or alkyl methacrylateswherein the alkyl group contains from 1 to 4 carbon atoms, such asmethyl, ethyl, propyl, or butyl methacrylates in the proportions fromabout 0.25 to 5 parts by weight of the said polymeric oxo-compound withone part by weight of an aminoguanidine compound such as aminoguanidinebicarbonate, aminoguanidine acetate, aminoguanidine butyrate, etc.; thereaction products of polyvinylsulfonates with C-aminopyridines ofReynolds et al. U.S. 2,768,078, issued Oct. 23, 1956, prepared byreacting alkyl and aryl polyvinyl sulfonates prepared as described inU.S. 2,531,468 and U.S. 2,531,469 both dated Nov. 28, 1950, undercontrolled conditions with C-aminopyridines or alkyl group substitutedC-aminopyridines such as 2-aminopyridine, 4-aminopyridine, theaminopicolines such as 2-amino-3-methylpyridine,2-amino-4-methylpyridine, 2-amino-S-methylpyridine,2-amino-6-methylpyridine and corresponding 4-aminomethyl derivativeswhich react in this reaction in exactly the same way, 2-amino-6-ethylpyridine, 2-amino-6-butylpyridine, 2-amino- 6-amylpyridine,etc.; the various aminotoluidines such as, for example,2-amino-3-ethyl-4-methyl pyridine, etc.; the dialkylaminoalkyl esters ofdialkylaminoalkylamides, e.g., such as those described by Carroll etal., U.S. Pat. 2,675,- 316, issued Apr. 13, 1954, prepared by reactingaddition polymers containing carboxyl groups 'with a basic dialkylaminocompound, for example, N-dialkylamine ethyl esters of polymers orcopolymers containing carboxyl groups; the addition type polymerscontaining periodically occurring quaternary groups of Sprague et al.US. 2,548,- 564, issued Apr. 10, 1951, including quaternary ammoniumsalts of vinyl substituted azines such as vinylpyridine and its homologssuch as vinyl quinoline, vinylacridine, and vinyl derivatives of othersix-membered heterocyclic ring compounds containing hydrogen atoms.These addition polymers include 2-vinylpyridine polymermetho-ptoluenesulfonate, 4-vinyl-pyridine polymermetho-p-toluenesulfonate.

Hardening materials that can be used to advantage in the describedlight-screening layer include such hardening agents as formaldehyde; ahalogen-substituted aliphatic acid such as mucobromic acid as describedin White US. Pat. 2,089,019, issued May 11, 1937; a compound having aplurality of acid anhydride groups such as 7.8diphenylbicyclo(2,2,2)-7-octene-2,3,5,6-tetra-carboxylic dianhydride, ora dicarboxylic or a disulfonic acid chloride such as terephthaloylchloride or naphthalene- 1.5-disulfon vl chloride as described in Allenand Carroll, U.S. Pats. 2,725,294 and 2,725,295, both issued Nov. 29,1955; a cyclic 1,2-diketone such as cyclopentane-1.2-dione as describedin Allen and Byers, US. Pat. 2,725,305, issued Nov. 29, 1955; a biesterof methanesulfonic acid such as 1,2-di(methanesulfonoxy)-ethane asdescribed in Allen and Laakso, US. Pat. 2,726,162, issued Dec. 6, 1955;1.3-dihydroxymethylbenzimidazoyl 2 one as described in July, Knott andPollak, US. Pat. 2,732,316, issued Jan. 24, 1956; a dialdehyde or asodium bisulfite derivative thereof, the aldehyde groups of which areseparated by 23 carbon atoms such as [ft-methyl glutaraldehydebis-sodium bisulfite as described in Allen and Burness US. PatentApplication Ser. No. 556,031, filed Dec. 29, 1955, now abandoned; abis-aziridine carboxamide such as trimethylene bis(1-aziridinecarboxamide) as described in Allen and Webster US. Pat. 2,950,197,issued Aug. 23, 1960; or 2,3-dihydroxydioxane as described in Jeifreys,US. Pat. 2,870,013, issued Jan. 20, 1959.

Photographic elements utliizing these novel light-screening layers haveli hbsensitive emulsion layers containing silver chloride, silverbromide, silver chlorobromide, silver iodide, silver bromoiodide, silverchlorobromoiodide, etc., as the light-sensitive material. The silverhalide emulsions may be sensitized by any of the sensitizers commonlyused to produce the desired sensitometric characteristics.

The dyes of this invention are valuable for preparing light-filteringlayers for light-sensitive photographic elements containing silverhalide emulsion layers. The lightfiltering layers containing these dyesare used to advantage, either over the light-sensitive silver halideemulsion layers, or between the light-sensiitve silver halide emulsionlayer and the support, between two different light-sensitive layers, oras an antihalation backing layer.

EXAMPLE 59 A solution containing Compound 12 dissolved in a mixture ofdimethylformamide and methyl alcohol is added to an aqueous gelatinsolution. The mixture is agitated thoroughly to ensure complete anduniform mixing. The resultant solution is coated on a film support sothat each square foot of support contains 300 mg. of gelatin and 240 mg.of dye. Superimposed on the thus formed filter layer is a conventionalphotographic silver halide emulsion layer. After drying, the element isexposed and developed by usual techniques. A sharp image is obtainedwith no discoloration due to residual dye in background areas. In thisexample, the dye was bleached by light energy absorbed during theexposure step. When this example is repeated without Compound 12, ablurred and fuzzy image is obtained because of the lack of filterprotection.

EXAMPLE 60 Example 66 is repeated except the dye employed is Compound 3and the silver halide emulsion used and photographic process employed isthat used in stabilized print out systems such as described in Example18 of Ser.

22 No. 625,590 filed Mar. 24, 1967, Bacon et a1. Again, a goodreproduction is obtained. The bleaching in this example is caused byboth light and heat energy.

HOLOGRAPHIC ELEMENTS The dyes of this invention are useful in thepreparation of holographic elements. The development of improvedholograms has been carried out on a continuous basis since theirintroduction in 1948 by Prof. D. Gabor. A typical system for laserholograms is described in Scientific American, February 1968, Vol. 218,No. 2, p. 43. Holograms have in the past been recorded with silverhalide emulsions. According to this portion of the invention the dyesdescribed herein can be used in holographic elements to recordholograms. Holograms produced in this manner have the advantage ofaffording higher resolution than the silver halide-based systems sincethe active particles are of molecular size (i.e., 10-35 A. for dyemolecules vs. 500 A. for very fine-grain silver halide particles).Another advantage is that no processing is'required since the dyes arephotobleachable (as explained previously) and the image is recordeddirectly. Therefore, dimensional stability is not a problem. Thereplacement of silver halide with the dyes of this invention is alsoeconomicalyy advantageous.

The holographic elements of this invention are prepared by mixing any ofthe dyes of this invention with a polymeric binder such aspolymethacrylate, gelatin, poly (vinylalcohol), etc. The composition iscoated on a support such as glass, Estar, cellulose acetate, Teflon,etc. The thickness of the coating may be varied from a few micronsupward.

EXAMPLE 61 A holographic element is prepared by mixing a solution of0.00793 g. of compound 18 in methanol (14 g.) with 36 grams of 28%poly(2-vinylpyridine) in methanol for about 17 hours. The resultingsolution is hand coated at room temperature on 5 x 7 inch glassspectroscopic plates using a knife setting of 0.030 in. The coating iscovered and allowed to dry slowly at room temperature.

EXAMPLE 62 A holographic element is prepared in the same manner asExample 68 except compound 11 is used instead of compound 18.

EXAMPLE 63 The elements of Examples 68 and 69 are used in the productionof laser holograms. The system employed is similar to that described inthe Scientific American article (op. cit.). A laser beam is divided by abeam splitter and directed by a combination of mirrors and lenses suchthat the reference beam impinges directly on the test coating while theother illuminates a ground glass object. The object used is a 1 cm.square spot of illuminated ground glass placed close to the holographicelement so that the reference beam and object beam illuminate an areaapproximately 1%" square on the coating. The exposure times range froml0-15 seconds with a 900 mw. laser. Each of the coatings produce goodrecordings of holographic fringes.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, and it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinabove and as defined in the appendedclaims.

We claim:

1. A heat-sensitive copying element comprising a support containing acompound having the formula:

wherein:

R is and acyl radical;

R and R are each selected from the group consisting of an aryl radical,a hydrogen atom and an alkyl radical; and

X is an acid anion.

2. The heat-sensitive element of Claim 1 wherein the compound is coatedon the support.

3. The heat-sensitive element of Claim 1 wherein the compound is imbibedinto the support.

4. The heat-sensitive element of Claim 1 wherein the compound isdispersed in a vehicle which is coated on the support.

5. A heat -sensitive image-forming composition comprising a compoundhaving a formula selected from the group consisting of:

Q Q and Q each represent the non-metallic atoms necessary to complete a5- to 6-membered heterocyclic ring;

11 is a positive integer from 1 to 4;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acylradical;

R is selected from the group consisting of an aryl radical, a hydrogenatom and an alkyl radical;

R and R are each cyano radicals;

R is selected from the group consisting of an alkyl radical, an alkenylradical, an aryl radical and an alkoxy radical; and

G is selected from the group consisting of an anilinovinyl radical andan aryl radical.

6. A heat-sensitive image-forming composition according to claim 5 inwhich said compound is defined by the formula:

Q and Q each represent the non-metallic atoms necessary to complete a 5-to 6-membered heterocyclic ring;

n is a positive integer from 1 to 4;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

24 R is selected from the group consisting of an alkyl and an acylradical; R is selected from the group consisting of an aryl radical, ahydrogen atom and an alkyl radical; and R is selected from the groupconsisting of an alkyl radical, an alkenyl radical, an aryl radical andan alkoxy radical. 7. A heat-sensitive image-forming compositionaccording to claim 5 in which said compound is defined by the formula:

wherein:

Q and Q each represent the non-metallic atoms necessary to complete a 5-to G-membered heterocyclic ring;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acylradical; and

R is selected from the group consisting of an aryl radical, a hydrogenatom and an alkyl radical. 8. A heat-sensitive image-forming compositionaccording to claim 5 in which said compound is defined by the formula:

wherein:

Q represents the non-metallic atoms necessary to complete a 5- tomembered heterocyclic ring;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acylradical; and

R is selected from the group consisting of an aryl radical, a hydrogenatom and an alkyl radical.

9. A heat-sensitive image-forming composition according to claim 5 inwhich said formula-defined compound is selected from the groupconsisting of:

(a) 3-ethyl-1-methoxy-2-pyridothiacarbocyanine iodide;

(b) 3-ethyl-l-methoXy-4,5'-benzo-2-pyridothiacarbocyanine perchlorate;

(c) 3-ethyl-1-methoxyoxa-Z'-pyridocarbocyanine perchlorate;

(d) 1-methoxy-l,3,3-trimethylindo-Z'-pyridocarbocyanine picrate;

(e) 3-ethyl-l-methoxy-2-pyridothiacyanine iodide;

and

(f) 3'-ethyl-l-methoxy-Z-pyridothiadicarbocyanine perchlorate.

10. A heat-sensitive copying element comprising a support and at leastone layer of a heat-sensitive composition comprising a compound having aformula selected from the group consisting of:

Q Q and Q each represent the non-metallic atoms necessary to complete a5,- to 6-mernbered heterocyclic ring;

n is a positive integer from 1 to 4;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acylradical;

R is selected from the group consisting of an aryl radical,

a hydrogen atom and an alkyl radical;

R is selected from the group consisting of an alkyl radical,

an alkenyl radical, an aryl radical and an alkoxy radical; and

G is selected from the group consisting of an anilinovinyl and an arylradical.

11. A heat-sensitive copying element comprising a support having thereonat least one layer of a heat-sensitive composition comprising a cyaninedye having a first and a second 5- to 6-membered nitrogen-containingheterocyclic nucleus joined by a methine linkage; the first of saidnuclei being selected from the group consisting of a l-alkoxypyridylnucleus and a l-alkoxyquinolyl nucleus, each of said first nuclei beingjoined at a carbon atom thereof to said linkage; and said second nucleusbeing a heterocyclic nucleus of the type contained in cyanine dyesjoined at a carbon atom thereof to said linkage, to complete saidcyanine dye.

12. A heat-sensitive copying element comprising a support having thereonat least one layer of a heat-sensitive composition comprising at leastone compound having the formula:

Q is selected from the group consisting of a pyridyl nucleus and aquinolyl nucleus;

Q represents the non-metallic atoms necessary to complete a 5- to6-membered heterocyclic ring;

X is an acid anion;

R is an alkyl radical;

R is selected from the group consisting of an aryl radical,

a hydrogen atom and an alkyl radical;

L is a methine linkage;

g is a positive integer from 1 to 2;

n is a positive integer from 1 to 4; and

26 R is selected from the group consisting of an alkyl radical, analkenyl radical, an aryl radical and an alkoxy radical. v 13. Aheat-sensitive copying element comprising a support and at least onelayer of a heat-sensitive composition comprising a compound having theformula:

wherein:

R is selected from the group consisting of an alkyl radical and an acylradical;

L is a methine linkage;

G is selected from the group consisting of an anilinovinyl radical and aphenyl radical;

m is a positive integer from 1 to 3;

X is an acid anion;

Q represents the atoms necessary to complete a 5- to '6- memberedheterocyclic ring; and

R is selected from the group consistin of an aryl radical,

a hydrogen atom and an alkyl radical.

14. The heat-sensitive copying element of claim 13 wherein saidheat-sensitive composition is imbibed into the support.

15. The heat-sensitive copying element of claim 13 whereinsaid-heat-sensitive composition is coated on the support.

16. The heat-sensitive copying element of claim 13 wherein saidformula-defined compound is dispersed in a vehicle which is coated onthe support.

17. A heat-sensitive image-forming element comprising a support havingcoated thereon a composition comprising gelatin and3'-ethyl-1-methoxy-4',5'-benzo-2-pyridothiacarbocyanine perchlorate.

References Cited UNITED STATES PATENTS 3,582,342 6/1971 Itano et al 9690R 3,597,212 8/1971 Webster et al 11736.8 X 3,615,432 10/1971 Jenkins etal 96--27 3,532,499 10/ 1970 Willams et a1 9666.3 3,770,451 11/1973Jenkins et a1. 96-135 THOMAS J. HERBERT, 1a., Primary Examiner US. Cl.X.R.

